JPH03229205A - Plastic optical fiber cord - Google Patents

Abstract

PURPOSE:To make improvement in heat resistance, low-temp. characteristic and mechanical characteristic by using a resin essentially consisting of methyl methacrylate for a fiber material and a resin having the structural unit of a vinylidene fluoride for a sheath material and coating fibers with a low-density polyethylene (LDPE). CONSTITUTION:The optical fiber is required to have a low loss and the excellent heat resistance, low-temp. characteristic and mechanical characteristic and, therefore, the resin compsn. essentially consisting of the methyl methacrylate is used for the fiber material. The resin compsn. contg. the structural unit of the vinylidene fluoride is used for the sheath material. Further, the outer side of the optical fiber is coated with the resin compsn. as to make improve ment in the heat resistance, mechanical strength and low-temp. characteristic. The value of the Shore D hardness at 23 deg.C of the fluorine-contained polyolefin resin compsn.. is >= 60 and further the elongation at rupture is specified to >=200%. The improvement in the transmission characteristic, heat resistance, mechanical characteristic, and low-temp. characteristic is made in this way.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a low-temperature optical fiber with excellent heat resistance, mechanical properties, and low-temperature properties that can be widely applied to FA, OA, automobiles, etc. for short-distance optical transmission. It is used between lossy plastic optical fiber cords.

(Prior art) Plastic optical fibers are more flexible than silica-based fibers, have large diameters, high numerical apertures, and are easy to process and connect, so they are used in fields such as short-distance communications and sensors. Applications have begun.

Conventional plastic optical fibers that have been put into practical use include those that use a resin mainly composed of methyl methacrylate for the core material and vinylidene fluoride copolymers or fluorinated methacrylate copolymers for the sheath material. Some use polycarbonate as the core material. It is also used as a plastic optical fiber cord by coating the outside of the sheath with polyethylene or polyvinyl chloride.

(Problem to be solved by the invention) Plastic optical fiber cords coated with polyethylene or polyvinyl chloride as described above can only be used at temperatures up to 85°C, and high heat resistance is required for automobiles. However, there were limited places where it could be applied.

In order to solve these problems, Japanese Patent Application Laid-Open No. 50-255
2 and Japanese Patent Application Laid-Open No. 60-254005 propose a plastic optical fiber in which a protective layer is provided just outside the sheath layer.

In particular, in the practice of JP-A-60-254005, the core layer,
A method is described in which three layers, a sheath layer and a protective layer, are composite-spun simultaneously and stretched to 1.5 times. However, in this method, the protective layer is also stretched, so when the temperature reaches around 100 degrees Celsius, the stretching is removed and the plastic optical fiber shrinks significantly, drastically reducing its optical transmission characteristics and mechanical strength. Heat resistance is still not sufficient.

(Means for Solving the Problems) The present invention has a structure in which the thermal shrinkage rate, optical transmission characteristics, and mechanical properties are less degraded even under high temperatures of 100° C. or higher and high temperature constant temperatures of 85° C. and 95% RH, and -20° C. The objective is to provide a plastic optical fiber cord that has excellent heat resistance, low-temperature properties, and mechanical properties, such as being resistant to breakage even at low temperatures of °C.

The present invention uses a resin mainly composed of methyl methacrylate as the core material, uses beet resin having a vinylidene fluoride structural unit as the sheath material, and coats the resin with low density polyethylene at a temperature of 85°C. 100 in a constant temperature and humidity chamber with a humidity of 95%
Immediately outside the plastic optical fiber, the change in transmission loss value (measured with 650 nm monochromatic light, incident aperture angle 0.15 radian, cutback method from 52 m to 2 m) when left for 0 hours is 100 dB/km or less. , the Shore D hardness value at 23°C is 60 or more, and the elongation at break (ASTM D1708 23°C tensile rate 100+n
The present invention is a plastic optical fiber cord having at least one layer coated with a coating resin composition characterized in that the coating resin composition has a coating resin composition characterized in that the plastic optical fiber cord has a coating resin composition characterized in that the coating resin composition has a speed (m/min) of 200% or more.

The present invention will be explained in detail below.

The plastic optical fiber strand consists of a core and a sheath.The plastic optical fiber strand of the present invention has low loss,
It must have excellent heat resistance, low-temperature properties, and mechanical properties. Therefore, a resin composition mainly containing methyl methacrylate was used for the core material. Specifically, the following resin compositions may be mentioned.

■Methyl methacrylate homopolymer ■Copolymer containing 50% by weight or more of methyl methacrylate, copolymerizable components include acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, and methacrylate. There are methacrylic esters such as ethyl methacrylate, propyl methacrylate, and cyclohexyl methacrylate, maleimides, methacrylic acid, acrylic acid, maleic anhydride, styrene, etc., and one or more of these can be appropriately selected and copolymerized. can.

The sheath material must be a resin composition with excellent transparency, heat resistance, mechanical properties, and low-temperature properties. .

Although fluorinated (meth)acrylate copolymers are amorphous and highly transparent, they are hard and brittle resins that have poor mechanical properties and
Because the adhesion with the core material is relatively poor, it is difficult to obtain sufficient mechanical properties and low-temperature properties as a cord.It also has poor chemical resistance, and its tensile strength and elongation decrease when soaked in plasticizers or alcohol. descend.

On the other hand, vinylidene fluoride copolymers have excellent heat resistance, mechanical properties, low-temperature properties, adhesion to core materials, and chemical resistance. However, under high temperatures of 100℃ or higher, or at 85℃95%
If left for a long time under the high temperature and high humidity conditions of RH, many fibers will crystallize and lose their transparency.In order to make a plastic optical fiber with a small increase in transmission loss, vinylidene fluoride, which can be used for the sheath, is recommended. The type of copolymer is limited to specific types.

As a result of intensive research by the present inventors, a specific vinylidene fluoride copolymer has high compatibility with the core material, a resin mainly composed of methyl methacrylate. It was found that during the melting and composite spinning stage, a highly transparent and uniform mixed layer in which the core material and sheath material were mixed with each other was formed at the interface between the core layer and sheath layer. For this reason, certain vinylidene fluoride-based sheath materials have excellent adhesion between the core and sheath, and the core and sheath do not separate even when the fiber is repeatedly subjected to tensile, twisting, or bending motions, and they do not allow plasticizers, etc. Even when immersed, there is little decrease in tensile properties. It was also found that the thickness of this mixed layer is related to the stability of the fiber's transmission loss under high temperature and high temperature and high humidity conditions.

If the thickness of the mixed layer is thin, the crystallization of the mixed layer will progress under high temperature or high humidity conditions, reducing transparency and increasing transmission loss for plastic optical fibers. A preferable thickness of the mixed layer is 0.6 μm or more, which improves durability against high temperatures and high temperatures and shows little change in transparency due to high temperatures and high humidity. Vinylidene fluoride copolymers that can form such a thick mixed layer include copolymers containing vinylidene fluoride and hexafluoroacetone, and copolymers containing vinylidene fluoride and hexafluoropropylene. can give. For example, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoroacetone copolymer, vinylidene fluoride-trifluoroethylene-
Hexafluoroacetone copolymer, vinylidene fluoride
Tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride
Hexafluoropropylene copolymer, etc.

These sheath materials are 2/1000 to 300/10 of the core diameter.
0.00 to obtain a plastic optical fiber strand. The manufacturing method uses a special nozzle and a two-layer extruder in a clean environment with almost no dust or debris to create a two-layer core-sheath structure by combining the core material and sheath material in a molten state. This is done using a composite spinning method that forms the material into a fiber that holds it. And 1.3
The plastic optical fiber is obtained by stretching the plastic optical fiber by a factor of 3.0 to 3.0 to orient the molecules to improve mechanical properties and strength. The plastic optical fiber strand manufactured in this way and used in the present invention has excellent not only mechanical properties and strength but also heat resistance. The heat resistance of a plastic optical fiber wire is determined by putting it in the form of a plastic optical fiber cord coated with low-density polyethylene on the outside and placing it in a constant temperature and humidity chamber at a temperature of 85°C and a humidity of 95% RH for 1000 hours. Evaluation is performed by measuring the amount of increase in transmission loss at a wavelength of 650 nm. In order to produce a plastic optical fiber cord with a small increase in transmission loss under high temperatures of 100° C. or higher and under high temperature and high humidity, it is preferable that the increase in transmission loss measured by this method is 100 dB/km or less. More preferably, it is 50 dB/km or less.

By using the specific vinylidene fluoride copolymer described above for the sheath material, it has become possible to reduce the increase in transmission loss even under high temperature and high humidity conditions. In addition, it can be used not only at room temperature but also at
It does not break immediately even if it is repeatedly subjected to bending or twisting at low temperatures such as 0°C. Furthermore, it is possible to produce a plastic optical fiber cord that is strong, has excellent mechanical properties, and has excellent chemical resistance, with little decrease in tensile strength and elongation even when immersed in plasticizers or alcohol.

The outer surface of the plastic optical fiber strand thus produced is coated with a specific resin composition to further improve heat resistance, mechanical properties, and low-temperature properties, and is used as a plastic optical fiber cord.

At high temperatures near or above 100°C, the core material, a resin composition mainly composed of methyl methacrylate, approaches the glass transition point, so the molecular orientation is removed and the plastic optical fiber undergoes significant heat shrinkage. transform. In order to prevent this, the transmission loss increases rapidly, and the coupling efficiency with the light source and photodetector is significantly reduced due to the sharp recess from the coating layer. Coat the resin composition. As a result of extensive study, we found that in order to prevent thermal shrinkage, deformation, and increase in transmission loss of plastic optical fiber strands under high temperatures, it is necessary to use a hard and creep-resistant coating layer (first coating layer) in contact with plastic optical fiber strands. It has been found that it is effective to coat a resin with small characteristics in such a way that it is not oriented as much as possible. In particular, fluorine-containing polyolefin resin has excellent heat resistance, mechanical properties, creep properties, and adhesion to plastic optical fibers, so it minimizes the thermal shrinkage of plastic optical fibers at high temperatures. be able to.

Such fluorine-containing polyolefin resins include vinylidene fluoride, a copolymer obtained by grafting vinylidene fluoride onto a random copolymer of vinylidene fluoride and chlorotrifluoroethylene, and a vinylidene fluoride-tetrafluoroethylene copolymer. , vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, chlorotrifluoroethylene polymer,
Furthermore, blends of the above-mentioned fluorinated polyolefin resins, blends of vinylidene fluoride resins and methyl methacrylate resins, blends of fluorinated polyolefin resins and olefin resins, and other known fluorinated polyolefin resins are also available. Basic polyolefin resins and blends of these and other resins can be used. Among these, it is preferable to use a resin composition containing at least a vinylidene fluoride structural unit. Resin compositions containing vinylidene fluoride structural units can be coated at relatively low temperatures among fluorine-containing polyolefin resin compositions, but they also have strong adhesion to the sheath material and have sufficient hardness and tensile strength, so they can be coated at high temperatures. It is possible to minimize the retraction of the plastic optical fiber strands underneath and the breakage, bending, and deformation of the plastic optical fiber cord.

However, the Shore D hardness value of these fluorine-containing polyolefin resin compositions at 23°C is 60 or more,
Furthermore, the elongation at break needs to be 200% or more. Here, Shore D hardness is at 23°C, ASTM D
2240, and the elongation at break is at a temperature of 23°C, ASTM D1708, and a tensile rate of 10.
This is a value measured at 0 forceps/min. If the Shore D hardness value is too small, the plastic optical fiber cord will easily deform under load or tension at high temperatures, which is undesirable as transmission loss will increase significantly.Also, the plastic optical fiber wire will shrink under high temperatures. If the elongation at break is small, the plastic optical fiber will retract significantly from the end face of the coating layer, reducing the coupling efficiency with the light source and photodetector. Bending and twisting can easily break plastic optical fiber cords, which is undesirable.
In a resin composition containing vinylidene fluoride structural units, the higher the content of vinylidene fluoride structural units, the higher the hardness, the stronger the tensile strength, and the better the creep properties, but the lower the tensile elongation at break. A preferable tensile elongation at break is 200% or more, more preferably 300% or more.

By using such a resin with high tensile elongation, the tensile elongation at break (AS) of the plastic optical fiber cord can be improved.
TM 638 Temperature 23℃ Tensile speed 100mm/
) becomes larger, becomes stronger in bending and tension, and improves mechanical properties. The preferred tensile elongation at break is 5.
It is 0% or more, more preferably 70% or more, and still more preferably 100% or more.

Then, this coating resin composition is preferably 0.0
Coat to a thickness of 5 to 0.50 mm. As a coating method, it is preferable to use a method in which a plastic optical fiber is produced by a composite spinning method, and then the outer surface is coated with a thermally melted coating resin composition. The coating layer, which has excellent heat resistance, has almost no orientation, so there is almost no thermal shrinkage even when exposed to high temperatures of 100"C or more. However, if the coating layer is too thin, it will not work properly even at room temperature. 7. At high temperatures of 100°C or higher, plastic optical fibers cannot be prevented from shrinking and withdrawing from the coating layer, and their durability against bending, twisting, and pulling is insufficient. If it is too large, the plastic optical fiber will be severely damaged by the heat from the coating resin composition melted at high temperatures, resulting in a large increase in transmission loss.Furthermore, the cord will be rigid and difficult to bend. ,
This is not preferred because it is difficult to handle. A more preferable thickness range is 0.05 to 0.2 mm.

In addition to the coating layer made of these fluorine-containing polyolefin resin compositions, it is also possible to stack several coating layers. In this case, other than the above-mentioned fluorine-containing polyolefin resin composition, known resin compositions can be used. For example, polyethylene, polypropylene, ethylene-vinyl alcohol copolymer, thermoplastic elastomer, polyvinyl chloride, cross-linked polyethylene, cross-linked polyvinyl chloride, chlorinated polyethylene compound, polyamide resin, silicone resin, thermosetting resin, ultraviolet curing resin, etc. It is. Further, as reinforcing fibers, aramid fibers, polyacetal fibers, ultra-high molecular weight polyethylene fibers, etc. may be interposed.

The plastic optical fiber cord of the present invention produced in this way has excellent transmission characteristics, heat resistance, mechanical properties, and low-temperature characteristics, and has almost no retraction or protrusion of the plastic optical fiber from the first coating layer. Has excellent properties.

(Example) Hereinafter, it will be explained based on an example. First, the measurement method will be explained.

・Shore D hardness It is carried out according to the method of ASTM D2240.

・Tensile breaking strength ■In the case of coating resin composition- Performed according to ASTM D1708.

Temperature: 23° C. Tensile speed: 100 mm/min ■For plastic optical fiber cord - Perform according to ASTM D638.

Measured using the cutback method at a temperature of 23°C, a tensile speed of 100 min/min, and a transmission loss of 52 m -2 m. 65 for light source
Uses 0 nm monochromatic light. Incident aperture angle 0.15 radian Measuring device: Fiber loss spectrometer FP-889, manufactured by Perex Corporation, low temperature repeated bending test Temperature: -20°C Bending angle = 180° Bending radius:
5mm Load: 500g cycle = 3 seconds Light source: 660nm LED/Length retention A plastic optical fiber cord was cut to a length of 1m, and the length was measured after leaving it in a constant temperature and humidity chamber under the specified conditions for 1000 hours. The length retention rate is calculated by the ratio of the length to 1 m.

・After cutting the retractable plastic optical fiber cord into a length of 1 m and leaving it in a constant temperature and humidity chamber under predetermined conditions for 1000 hours, the end face of the first coating layer and the end face of the plastic optical fiber strand are separated. Measure the difference in position.

(Shukushita Kiusu) (Example 1) As a plastic optical fiber, a resin mainly composed of methyl methacrylate was used as the core material, and a vinylidene fluoride-trifluoroethylene-hexafluoroacetone copolymer was used as the sheath material. Luminous FB-1000 manufactured by Asahi Kasei Kogyo Co., Ltd. with a diameter of 1°00 mm was used, and vinylidene fluoride was used as the coating resin composition used for the coating layer (first coating layer) in contact with this plastic optical fiber wire. Resin KY
Produced by mixing NAR740 (manufactured by Pennwalt) and soft fluorine-containing polyolefin resin Cepural Soft G150 (manufactured by Central Glass), Shore D hardness at 23°C 74. Tensile elongation at break at 23°C 400%
I used something that is.

This FB-1000 has low density polyethylene (NUC9
The amount of increase in transmission loss after placing a plastic optical fiber cord with a diameter of 2.2 mmφ coated with 109 (manufactured by Nippon Unicar Co., Ltd.) to a thickness of 0.6 mm in a constant temperature and humidity chamber at 85°C and 95% RH for 1000 hours is , 35 dB/km. In addition, the cross section of FB-1000 was examined using a transmission electron microscope.
When observed using Hitachi H-500, there was a mixed layer between the core layer and sheath layer, and the thickness was 1.4μ.
It was m.

The above plastic optical fiber strand was introduced into a die directly connected to a melt extruder, and the above coating resin composition was applied to a die of 0-1
A plastic optical fiber cord coated to a thickness of 50 mm and having a diameter of 1.30+n+n was produced.

Furthermore, this plastic optical fiber cord was guided to a die directly connected to the melt extruder in the same manner as above, and coated with polyvinyl chloride resin to a diameter of 3 to 0 mm to produce the plastic optical fiber cord of the present invention. did.

The optical wavelength of this plastic optical fiber cord is 650n.
A fiber loss spectrometer is used to measure the transmission loss at m.
Using FP-889 (manufactured by Operax), 52m-2
When measured using the cutback method of m, it was 132 dB/k.
m, and there was almost no increase in loss due to encoding.

Next, this plastic optical fiber cord was subjected to a tensile test. Measurement was performed using a tensile tester 5HINKoH model T
The test was carried out using OM-500 and a method according to ASTM D638 at a temperature of 23° C. and a tensile speed of 100 mm/min. The tensile breaking load at this time was 18.4 kg and the breaking elongation was 120%, indicating sufficient tensile strength and breaking elongation.

Next, dry heat the plastic optical fiber cord for 10 minutes.
Leave it in a constant temperature oven at 5℃ for 1000 hours, and the light wavelength 6
Changes in transmission loss at 50 nm were measured. At the time of manufacture 1
The loss was 32 dB/km, but it was 176 dB/km even after being left for 1000 hours, so the increase in loss was small.Moreover, the length retention rate of the first coating layer was 99.1%, which was hardly any shrinkage. There was almost no retraction of the plastic optical fiber strand from the first coating layer at the end face, which was only 0.1 mm, and excellent heat resistance was exhibited. Also, the temperature is 85℃9
Leave it in a constant temperature and humidity chamber at 5% RH for 1000 hours,
Similarly, when we measured the change in transmission loss at an optical wavelength of 650 nm, we found that the transmission loss, which was 132 dB/km at the time of manufacture, was
Even after 1000 hours, it was 168 dB/km, and the heat and humidity resistance was also excellent.

Next, this plastic optical fiber cord was heated to a temperature of -2
A low temperature repeated bending test was conducted at 0°C. The test conditions are shown below, and the state of this test is shown in FIG.

Temperature knee 20℃ Bending radius = 511II11 Load:
500g Fiber length: 5m Period: 3 seconds Light source: 660nm LED As a result, the fiber did not break even after repeated bending 2000 times. Power wire (JIS C3307 copper 1.2mm
φ Primary coating Polyvinyl chloride 2.8 φ) Compared to the number of ruptures of 160, it exhibited significantly superior low-temperature bending properties.

(Example 2) Luminous FB-1000 manufactured by Asahi Kasei Corporation and having a diameter of 111 IIφ, which is the same as that used in Example 1, was used as the plastic optical fiber strand, and used for the coating layer in contact with this plastic optical fiber strand. The coating resin composition was prepared by mixing vinylidene fluoride resin KYNAR 740 (manufactured by Pennwalt Co., Ltd.) and soft fluorine-containing polyolefin resin Cepural Soft G150 (manufactured by Central Glass Co., Ltd.), and had a Shore D hardness of 74.23 at 23°C.
A material having a tensile elongation at break of 400% at °C was used.

The plastic optical fiber strand was introduced into a die directly connected to a melt extruder, and the coating resin composition was applied at a rate of 0.1
A plastic optical fiber cord of the present invention coated to a thickness of 5 On+m and having a diameter of 1.30 mm was prepared.

The optical wavelength of this plastic optical fiber cord is 650
When the transmission loss in nm was measured in the same manner as in Example 1, it was 130 dB/km, and there was almost no increase in loss due to coding.

Next, this plastic optical fiber cord was subjected to a tensile test in the same manner as in Example 1. At this time, the tensile breaking load is 1
The weight was 2.5 kg, and the elongation at break was 120%, indicating sufficient tensile strength and elongation at break.

Next, dry heat the plastic optical fiber cord for 10 minutes.
Leave it in a constant temperature oven at 5℃ for 1000 hours, and the light wavelength 6
Changes in transmission loss at 50 nm were measured. At the time of manufacture 1
The loss was 30 dB/km, but it was 181 dB/km even after being left for 1000 hours, so the increase in loss was small.Moreover, the length retention rate of the first coating layer was 99.1%, which was hardly any shrinkage. , the retraction of the plastic optical fiber from the first coating layer at the end face is also 0-1m! It exhibits excellent heat resistance, and has a temperature of 85℃.
It was left in a constant temperature and humidity chamber at 95% RH for 1000 hours, and changes in transmission loss at an optical wavelength of 650 nrn were similarly measured. What was 130 dB/km at the time of manufacture was 171 dB/km even after 1,000 hours, showing excellent moisture and heat resistance.

Next, Example 1 was applied to this plastic optical fiber cord.
A low temperature repeated bending test at a temperature of -20°C was conducted in the same manner as above. As a result, it did not break even after repeated bending 2000 times, and exhibited excellent low-temperature bending properties.

(Example 3) Asahi Kasei Co., Ltd. used a resin mainly composed of methyl methacrylate as a core material and a vinylidene fluoride-trifluoroethylene-hexafluoroacetone copolymer as a sheath material as a plastic optical fiber wire. Made with a diameter of 0.80mmφ
Luminous FB-800 was used, and vinylidene fluoride resin KY was used as the coating resin composition used for the coating layer (first coating layer) in contact with the plastic optical fiber strand.
Produced by mixing NAR740 (manufactured by Pennwalt) and soft fluorine-containing polyolefin resin Cefural Soft G180 (manufactured by Central Glass), Shore D hardness at 23°C 68. Tensile elongation at break at 23°C 410%.
I used something that is. Add 0.5% of low density polyethylene (NtJC9109 manufactured by Nippon Unicar Co., Ltd.) to this FB-800.
The increase in transmission loss after placing a plastic optical fiber cord with a diameter of 1.8 mmφ coated to a thickness of nc+ in a constant temperature and humidity chamber at a temperature of 85°C and 95% RH for 1000 hours is 45
It was dB/km. In addition, when the cross section of FB-800 was observed using a transmission electron microscope Hitachi H-500, a mixed layer of both core layer and sheath layer existed, and its thickness was 1.2 μm. there were.

The plastic optical fiber strand was introduced into a die directly connected to a melt extruder, and the coating resin composition was applied at a rate of 0.1
A plastic optical fiber cord having a diameter of 1.00 mm was produced by coating the fiber to a thickness of 00 m+a.

Furthermore, in the same manner as above, this plastic optical fiber cord was guided to a die directly connected to the melt extruder and coated with polyvinyl chloride resin to a diameter of 2.2 mm, thereby producing the plastic optical fiber cord of the present invention. did.

The optical wavelength of this plastic optical fiber cord is 650n.
A fiber loss spectrometer is used to measure the transmission loss at m.
Using FP-889 (manufactured by Operax), 52m-
When measured with a 2m cutback method, it was 143dB/
km, so there is almost no increase in loss due to coding.

Next, this plastic optical fiber cord was subjected to a tensile test. Measurement is done using tensile tester SHI NKOH model
The test was carried out using TOM-500 and a method according to ASTM D638 at a temperature of 23° C. and a tensile speed of 100 mo/min. The tensile breaking load at this time was 12.8 kg, the breaking elongation was 130%, and sufficient tensile strength and breaking IgrM
It showed 1 degree.

Next, dry heat the plastic optical fiber cord for 10 minutes.
Leave it in a constant temperature oven at 5℃ for 1000 hours, and the light wavelength 6
Changes in transmission loss at 50 nm were measured. At the time of manufacture 1
What was 43 dB/km was 183 dB/km even after being left for 1000 hours, and the increase in loss was small. Moreover, the length retention rate of the first coating layer is 98.5%, which is not significantly reduced, and the retraction of the plastic optical fiber from the first coating layer at the end face is hardly 0.1 mm or less. It showed excellent heat resistance. Also, the temperature is 85℃
The sample was left in a constant temperature and humidity chamber at 95% RH for 1000 hours, and changes in transmission loss at a light wavelength of 650 nm were similarly measured. What was 132dB/km at the time of manufacture was 10
Even after 00 hours, it was 190 dB/km, and the heat and humidity resistance was also excellent. Next, this plastic optical fiber cord was subjected to a low temperature repeated bending test at a temperature of -20°C. As a result, even though the film was repeatedly bent 2000 times, it did not break and showed extremely excellent low-temperature bending properties.

(Example 4) Luminous FB-800 manufactured by Asahi Kasei Industries, Ltd., which is the same as in Example 3, was used as the plastic optical fiber strand, and as a coating resin composition used for the coating layer in contact with this plastic optical fiber strand, Vinylidene fluoride resin KY
It is made by mixing NAR740 (manufactured by Pennwalt) and soft fluorine-containing polyolefin resin Cepural Soft G180 (manufactured by Central Glass), and has a hardness of Shigor D at 23°C and a tensile elongation at break of 410 at 23°C.
% was used. The plastic optical fiber strand of the present invention is introduced into a die directly connected to a melt extruder, and coated with the coating resin composition to a thickness of 0.100 mm to produce a plastic optical fiber of the present invention having a diameter of 1 to 00 mm. I created the code.

The optical wavelength of this plastic optical fiber cord is 650n.
When the transmission loss at m was measured in the same manner as in Example 1, it was L41 dB/km, and there was almost no increase in loss due to coding.

Next, this plastic optical fiber cord was subjected to a tensile test in the same manner as in Example 1. At this time, the tensile breaking load is 9
．． The weight was 2 kg, and the elongation at break was 140%, indicating sufficient tensile strength and elongation at break.

Next, dry heat the plastic optical fiber cord for 10 minutes.
Leave it in a constant temperature oven at 5℃ for 1000 hours, and the light wavelength 6
Changes in transmission loss at 50 nm were measured. At the time of manufacture 1
What was 41 dB/km was 185 dB/km even after being left for 1000 hours, and the increase in loss was small. Moreover, the length retention rate of the first coating layer is 98.5%, which shows almost no shrinkage, and the retraction of the plastic optical fiber from the first coating layer at the end face is almost 0.1 am or less, which is excellent. It showed excellent heat resistance. Also, heat 85
Leave it in a constant temperature and humidity chamber at 95% RH for 1000 hours, and similarly measure the change in transmission loss at a wavelength of 650 nm.It was 141 dB/km at the time of manufacture, but it was still 192 dB after 1000 hours. /km, and has excellent moisture and heat resistance.

Next, Example 1 was applied to this plastic optical fiber cord.
A low temperature repeated bending test at a temperature of -20°C was conducted in the same manner as above. As a result, it did not break even after repeated bending 2000 times, and showed very excellent low-temperature bending properties.

(Example 5) Luminous FB-1000 manufactured by Asahi Kasei Corporation and having a diameter of 1 mmφ, which is the same as that used in Example 1, was used as the plastic optical fiber strand, and used for the coating layer in contact with this plastic optical fiber strand. The coating resin composition was prepared by mixing vinylidene fluoride resin KYNAR 740 (manufactured by Pennwald Co., Ltd.) and soft fluorine-containing polyolefin resin Cepural Soft G150 (manufactured by Central Glass Co., Ltd.), and had a Shore D hardness of 74. 23
A material having a tensile elongation at break of 400% at °C was used.

The above plastic optical fiber cord was introduced into a die directly connected to a melt extruder, and the above coating resin composition was applied to (L
A plastic optical fiber cord coated to a thickness of 150 mm and having a diameter of 1.30 mm was produced.

Furthermore, this plastic optical fiber cord is guided to a die directly connected to the melt extruder in the same manner as above, and vinylidene fluoride resin KYNAR740 (manufactured by Pennwalt) and soft fluorine-containing polyolefin resin Cepural Soft G are used.
A plastic optical fiber cord having a diameter of 2.2 mm was prepared by coating the resin composition mixed with 180 to a thickness of 0.45 mm. The Shore D hardness of this resin composition was 68, and the tensile elongation was 410%.

The optical wavelength of this plastic optical fiber cord is 650 nm.
When the transmission loss was measured in the same manner as in Example 1, it was 130 dB/km, and there was almost no increase in loss due to coding.

Next, we conducted a tensile test on this plastic optical fiber cord.
It was carried out in the same manner as in Example 1. At this time, the tensile yield load was 15.0 kg, and the elongation at break when all the cords were broken was 140%, indicating sufficient tensile strength and elongation at break.

Next, dry heat the plastic optical fiber cord for 10 minutes.
The sample was left in a constant temperature bath at 5°C for 1000 hours, and changes in transmission loss at an optical wavelength of 650 nm were measured. The one that was 130 dB/km at the time of manufacture was
Even after 00:00 dark broadcasting, the loss was 175 dB/km, and the increase in loss was small. Moreover, the length retention rate of the plastic optical fiber cord is 99.3%, which shows almost no shrinkage, and the plastic optical fiber strand is pulled from the coating layer at the end face. There was almost no retraction of 0.1 mm or less, demonstrating excellent heat resistance. Also, heat 85
The sample was left in a constant temperature and humidity chamber at 95% RH for 1000 hours, and changes in transmission loss at a light wavelength of 650 nm were similarly measured. What was 130dB/km at the time of manufacture was 1
168 dB/km even after 000 hours,
It also has excellent moisture and heat resistance.

Next, Example 1 was applied to this plastic optical fiber cord.
A low temperature repeated bending test was conducted at a temperature of -20'C.

In this case, it did not break even after being repeatedly bent 2000 times, and showed very excellent low-temperature bending properties.

Comparative Example 1) A plastic optical fiber cord was produced in the same manner as in Example 1, except that vinylidene fluoride-tetrafluoroethylene copolymer was used as the sheath material. However, this plastic optical fiber has low density polyethylene (NUC).
9109 manufactured by Nippon Unicar Co., Ltd.) coated with a thickness of 0.6mo+ and a diameter of 2. A 2mmφ plastic optical fiber cord was placed in a constant temperature and humidity chamber at 85°C and 95% RH for 100 minutes.
The increase in transmission loss after 0 hours was 257dB/
It was km. In addition, when we observed the cross section of this plastic optical fiber cord using a transmission electron microscope, we found that
There was a mixed layer between the core layer and the sheath layer, and the thickness was 0.3 μm.

The transmission loss during manufacturing is 164 dB at an optical wavelength of 650 nm.
/km, but the transmission loss after 1000 hours at a dry temperature of 105℃ was 680dB/km, and at a temperature of 85℃95
The transmission loss after 1200 hours of %RH was 850 dB/km, and the heat resistance and heat and humidity resistance were poor.

(Comparative Example 2) A plastic optical fiber cord was produced in the same manner as in Example 1 except that a fluorinated methacrylate copolymer was used for the sheath material. When the cross section of this plastic optical fiber cord was observed using a transmission electron microscope, no mixed layer was found between the core layer and the sheath layer.

When this plastic optical fiber cord was subjected to a repeated bending test at a temperature of -20° C. similar to that in Example 1, it broke after 200 times.

(Comparative Example 3) Vinylidene fluoride resin KYNAR710 (
A plastic optical fiber cord having a diameter of 2.2 north φ was prepared by coating the fiber to a thickness of 0.6 mm. However, vinylidene fluoride resin KYNAR
710 has a Shore D hardness of 81 and a tensile elongation at break of 120%.
Met.

The transmission loss of this plastic optical fiber cord is 800
In addition to being extremely large at dB/km, the tensile elongation at break is 15%.
Unfortunately, it broke immediately. Also, when the cord was bent, the surface of the vinylidene fluoride layer immediately cracked.

(Comparative Example 4) A soft fluorine-containing polyolefin resin Cepural Soft G150 (manufactured by Central Glass Co., Ltd.) was used for the coating layer in contact with the plastic optical fiber FB-1000,
Thickness 0.3L! Divide into two times of Im each time, total thickness 0.6
A plastic optical fiber cord having a diameter of 2°2no was prepared by coating the fiber with a thickness of 0.0111m. However, the soft fluorine-containing polyolefin resin Cephural Soft G150 had a Shore D hardness of 49 and a tensile elongation at break of 440%.

When this plastic optical fiber cord was placed in a dry thermostat at 105° C. for 1000 hours, the plastic optical fiber strands of the cord had a total length of 1 m and were retracted by 2.0> from the end face of the coating layer.

Furthermore, the transmission loss at an optical wavelength of 650 nm also increased from 140 dB/km at the time of manufacture to 370 dB/km.

(Comparative Example 5) The plastic optical fiber strand produced in Comparative Example 2 was coated with low-density polyethylene to a thickness of 0.60+ nm to produce a 2.2 inch plus deck optical fiber cord. However, the Shore D hardness of low density polyethylene is 48,
The tensile elongation at break was 690%.

When this plastic optical fiber cord was placed in a dry thermostat at 105°C for 200 hours, the coating layers were stuck together, and the plastic optical fiber strand had shrunk significantly and was recessed by 8.3 marks from the end face. It was not in a usable condition.

(Effects of the Invention) From the above results, the plastic optical fiber cord of the present invention not only exhibits excellent heat resistance with extremely small loss increase and thermal shrinkage even at high temperatures exceeding 100°C, but also exhibits excellent tensile resistance. It is stretchable and difficult to break, and the temperature is -20℃.
It also has excellent mechanical properties, such as being resistant to repeated bending under such harsh environments. In addition, since the retraction of the plastic optical fiber from the first coating layer is small, there is no need to strip the entire coating when attaching a connector, reducing the number of work steps.Furthermore, since the coating layer remains attached, heat resistance is improved. The present invention, which has the advantage of being able to be installed without dropping it, enables the application of plastic optical fibers to fields that require severe heat resistance and mechanical properties, such as automobiles.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a bending test.

Claims (1)

[Claims] A plastic optical fiber using a resin composition mainly composed of methyl methacrylate as the core material and a resin composition containing at least a vinylidene fluoride structural unit as the sheath material, and coated with low-density polyethylene. , temperature 85℃
, transmission loss value when left in a constant temperature and humidity chamber at 95% humidity for 1000 hours (incidence aperture angle 0.15 with 650 nm monochromatic light)
radian, Shore D hardness at 23°C (A
STMD2240) value is 60 or more, and tensile elongation at break (ASTMD1708 23°C tensile rate 100
1. A plastic optical fiber cord having at least one layer coated with a fluorine-containing polyolefin resin composition, characterized in that the fiber optics (mm/min) is 200% or more.